1. Field of the Invention
The present invention relates to a method of decoding a color based image code, and more particularly, to a method of classifying a color of each cell of an image code during a decoding process.
2. Description of the Related Art
For the past decade, an augmented reality and a mixed reality service using black and white patterned barcodes, and commercial services, such as mobile commerce, have been researched. Recently, a color based image code, such as a color code, for a mobile computer has been suggested. However, the colors of color cells forming the color based image code change depending on the lighting, printing media, and conventional cameras, and thus, it is difficult to recognize the color based image code as compared to a black and white markers.
Recent researches have focused on a user interface that provides data or services in a virtual world to a user by embedding tag media in a physical object and recognizing the physical object using a reader. Tag media used in a tangible user interface can be divided into a wireless tag, such as a radio frequency identification (RFID), and an image code, such as a barcode. Specifically, an interface, which provides service by recognizing an image of an image code or a marker, is called a paper user interface (PUI). Such interface method is used in studying an augmented reality and a mixed reality service, and commercial services, such as a personal information management service (PIMS), advertisement service, mobile commerce, etc. using a mobile phone.
An image code and a marker can be divided into a 1D barcode and a 2D code. The 1D barcode illustrates identifying numbers, checksum digits, and guide bars using pattern information in black and white bars. The 2D code has an error correction capacity using security information since the 2D code can store a larger amount of data than the 1D barcode. FIG. 1 is a diagram of examples of 2D codes from among conventional color based image codes.
A conventional terminal used in a mobile computing environment is formed with a low capacity memory, a low performance processor, and a conventional user built-in camera, and thus, the conventional terminal has following constraints in terms of recognizing an image.
First, a PUI should be able to be used under various lighting in everyday life. Second, a recognition algorithm should be simple and quick and third, an image should be recognized using a low performance camera. Examples of a 2D code considering such constraints include a cyber code, a quick response (QR) code limiting the number of cells, and a color code where, a barcode, the cyber code, and the QR code are formed of black and white cells as patterns, and the color code is a color based image code.
Most codes are black and white since black and white can be easily recognized as compared to other colors. However, as color media becomes popularized, a color based image code, which is media-friendly and requires large data storage capacity as compared to a conventional black and white code, has come into the spotlight.
In color based image codes such as a color code, an identifier is encoded using colors, and error verification and direction detection functions using double parity technology are provided. An algorithm of decoding a color code is very simple and efficient against a blur phenomenon since data is represented not in terms of a length pattern of cells, however, in color cells having the same size. However, a color change in a color based image code, such as a color code in a mobile computing environment according to various lighting, camera characteristics, and printing media characteristics makes it difficult to recognize the color based image code.